//找到新增按钮
let btn = document.querySelector('.btn')
let ul = document.querySelector('.add-wrap')
btn.onclick = function () {
    let re = getLi()
    ul.appendChild(re)
}

//创建li
function getLi() {
    let li = document.createElement('li')
    let input = document.createElement('input')
    input.setAttribute('placeholder', '请输入内容')
    li.appendChild(input)
    console.log(li);
    return li
}